The Structural, Dielectric, Lattice Dynamical and Thermodynamic Properties of Zinc-Blende CdX (X= S, Se, Te) from First-Principles Analysis
FENG Shi-Quan1**, LI Jun-Yu1, CHENG Xin-Lu2
1School of Physicas and Electronic Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002 2Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065
Abstract：The structural, dielectric, lattice dynamical and thermodynamic properties of zinc-blende CdX (X=S, Se, Te) are studied by using a plane-wave pseudopotential method within the density-functional theory. Our calculated lattice constants and bulk modulus are compared with the published experimental and theoretical data. In addition, the Born effective charges, electronic dielectric tensors, phonon frequencies, and longitudinal optical-transverse optical splitting are calculated by the linear-response approach. Some of the characteristics of the phonon-dispersion curves for zinc-blende CdX (X= S, Se, Te) are summarized. What is more, based on the lattice dynamical properties, we investigate the thermodynamic properties of CdX (X= S, Se, Te) and analyze the temperature dependences of the Helmholtz free energy F, the internal energy E, the entropy S and the constant-volume specific heat Cv. The results show that the heat capacities for CdTe, CdSe, and CdS approach approximately to the Petit-Dulong limit 6R.
2015, Vol. 32 
